An image pickup lens unit included in mobile phones has a structure in which a periphery of an optical lens for imaging is held by a holder. Typically, the optical lens is mounted into the holder by an automatic assembly system that has a very high positioning accuracy and uses an image recognition technique. However, such a system is not only very costly, but also requires a very large space because production lines are set up for different steps, such as a step of inserting a lens into a holder and a step of bonding the lens to the holder. As a result, facility replacement carried out for each change of lens type involves very extensive work, and hence many worker-hours are required.
A manufacturing method that addresses the problems described above is known. In this method, after an optical glass lens and a stop (or diaphragm) are positioned and set in a mold in advance, a holder is formed around the optical glass lens by injection molding to assemble an image pickup lens unit at the same time (see PTL 2).
In the manufacturing method described in PLT1, by setting the lens and the stop with a positioning member which is formed in the mold so as to extend along a side surface of the lens and the stop, the positioning is performed with respect to the mold. Accordingly, an operation of the positioning between the holder and the lens is not necessary and it is possible to reduce the number of components. However, since a positioning shape which is generated when the positioning is performed by abutting the optical lens or the stop before molding, remains as a deep hollow on a portion of a molded product facing the side surface of the optical lens or the like, optical problems such as a ghost or flare caused by unnecessary light in the position thereof can be generated. Also, visual specifications required for the image-pickup lens unit to be included in products, such as image-pickup apparatuses, may not be met. In addition, it is not possible to manufacture a small image pickup lens unit which is required for an image pickup lens unit built in a portable device, for example, a mobile, phone. Also, such a positioning shape may cause deformation during mold releasing and may deteriorate the dimensional accuracy. Further, in the above method for manufacturing, since the optical glass lens or the like is positioned and fixed by holding the optical glass lens between molds, there is a concern of damaging the optical glass lens at the time of the fixing.